title: N-aralkylated derivatives of 1-aminobenzotriazole as isozyme-selective, mechanism-based inhibitors of guinea pig hepatic cytochrome P-450 dependent monooxygenase activity.
abstract: The mechanism-based inactivation of hepatic cytochrome P-450 by the suicide inhibitor 1-aminobenzotriazole and two of its derivatives, N-benzyl-1-aminobenzotriazole and N-alpha-methylbenzyl-1-aminobenzotriazole, was investigated in microsomes from untreated, phenobarbital-induced, and beta-naphthoflavone-induced guinea pigs. Microsomal 7-ethoxyresorufin O-deethylase, 7-pentoxyresorufin O-dealkylase, and benzphetamine N-demethylase activities, and cytochrome P-450 content were determined following incubation with 1-aminobenzotriazole and its analogues. The loss of hepatic cytochrome P-450 content and monooxygenase activity was dependent on inhibitor concentration and required NADPH. N-Benzyl-1-aminobenzotriazole and N-alpha-methylbenzyl-1-aminobenzotriazole were more potent inhibitors of monooxygenase activity than the parent compound in microsomes from untreated and phenobarbital-induced guinea pigs. In microsomes from phenobarbital-induced guinea pigs, N-alpha-methylbenzyl-1-aminobenzotriazole (10 microM) was highly selective for the inactivation of the major cytochrome P-450 isozyme catalyzing 7-pentoxyresorufin O-dealkylation (the guinea pig ortholog of P-450IIB1) compared with those isozymes catalyzing 7-ethoxyresorufin O-deethylation or benzphetamine N-demethylation (88 +/- 3% loss of activity vs. 35 +/- 11 and 13 +/- 7%, respectively). N-Benzyl-1-aminobenzotriazole was also selective for the inactivation of 7-pentoxyresorufin O-dealkylase activity, but to a lesser degree (56 +/- 6 vs. 31 +/- 8 and 21 +/- 8%, respectively). In hepatic microsomes from untreated guinea pigs, the two N-substituted analogues were selective for the inhibition of 7-pentoxyresorufin O-dealkylation compared with benzphetamine N-demethylation, but not 7-ethoxyresorufin O-deethylation.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Pharmacology and Toxicology, University of Western Ontario, London, Canada.
authors.forename: K J
authors.initials: KJ
authors.lastname: Woodcroft
authors.forename: J R
authors.initials: JR
authors.lastname: Bend
mesh_terms: D000818:Animals; D001571:Benzoflavones / Q000494:pharmacology; D019363:Cytochrome P-450 CYP1A1; D019362:Cytochrome P-450 CYP2B1; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D005260:Female; D006168:Guinea Pigs; D007527:Isoenzymes / Q000037:antagonists & inhibitors* / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000201:enzymology* / Q000648:ultrastructure; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism; D010089:Oxidoreductases, N-Demethylating / Q000037:antagonists & inhibitors / Q000378:metabolism; D010634:Phenobarbital / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology*; D019324:beta-Naphthoflavone
chemical_list: D001571:Benzoflavones; D065607:Cytochrome P-450 Enzyme Inhibitors; D007527:Isoenzymes; D014230:Triazoles; C067013:N-benzyl-1-aminobenzotriazole; C059849:alpha-methylbenzylaminobenzotriazole; C033020:1-aminobenzotriazole; D019324:beta-Naphthoflavone; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases; D019363:Cytochrome P-450 CYP1A1; D019362:Cytochrome P-450 CYP2B1; C019781:benzphetamine N-demethylase; D010089:Oxidoreductases, N-Demethylating; D010634:Phenobarbital